Pasteurized milk beverage and production method for same

Abstract

This pasteurized milk beverage which contains milk protein and calcium, which has a pH at 25°C of 5.0 or less, in which the milk protein contains whey protein and the whey protein content is 40 mass% or more with respect to the total mass of the proteins contained in the pasteurized milk beverage, and which contains a phosphate and an acidified milk stabilizer has good solution stability despite containing milk protein and calcium and having a low pH.

Description

Sterilized milk drink and its manufacturing method

[0001] The present invention relates to a pasteurized milk beverage and a method for producing the same. This application claims priority to Japanese Patent Application No. 2023-150088, filed on September 15, 2023, the contents of which are incorporated herein by reference.

[0002] For example, typical sour milk drinks, such as drinking yogurt, are produced by adding lactic acid bacteria to pasteurized (also known as primary pasteurization) milk raw material liquid and fermenting it. Because sour milk drinks produced in this way contain lactic acid bacteria, they must be stored refrigerated. It is known that typical sour milk drinks have poor liquid stability during storage. For example, when sour milk drinks are stored, milk proteins aggregate over time, forming a clear layer on top (also known as syneresis). Syneresis is considered undesirable in terms of product appearance.

[0003] On the other hand, a sour milk drink that can be stored at room temperature can be produced by heat sterilization (also known as secondary sterilization) after fermentation. However, if secondary sterilization is performed in a state where the pH has been lowered by fermentation, aggregation of milk proteins is promoted during sterilization, which is likely to result in quality degradation such as a rough texture, excessive thickening, and / or accelerated syneresis during storage. The rate at which syneresis progresses during storage is affected by the storage temperature, and syneresis tends to be more accelerated when stored at room temperature than when stored refrigerated.

[0004] In recent years, with the background of a super-aging society, there has been an increasing need for foods with increased (also called fortified) content of specific nutrients such as calcium. Patent Document 1 relates to a method for producing a high-protein, acidic liquid dairy product using whey protein and fortified with calcium ions and magnesium ions. Patent Document 1 describes a method for producing an acidic liquid dairy product by heat sterilizing a high-protein milk raw material liquid, adding a starter, and fermenting (i.e., acidifying) the liquid, the method including adding a milk mineral composition containing calcium or CaCl ２ In one example, the above was added after heat sterilization of the milk raw material liquid and before fermentation.

[0005] Japanese Patent No. 7212624

[0006] Calcium naturally contained in milk is known to be relatively stable even in sour milk beverages. However, adding calcium separately from milk tends to promote syneresis and precipitation to the bottom during storage, and especially when secondary sterilization is performed, there are problems such as excessive aggregation and significant thickening. For this reason, it has been more difficult to perform secondary sterilization on sour milk beverages with low pH and calcium fortification to make them storable at room temperature.

[0007] The present invention has been made in consideration of the above circumstances, and aims to provide a novel pasteurized milk beverage that contains milk protein and calcium and has good liquid stability despite having a low pH.

[0008] The present invention has the following aspects. [1] A sterilized milk beverage containing milk protein and calcium, wherein the pH at 25°C is 5.0 or less, the milk protein comprises whey protein, the whey protein content is 40% by mass or more relative to the total mass of protein contained in the sterilized milk beverage, and the sterilized milk beverage contains a phosphate and an acid milk stabilizer. [2] The sterilized milk beverage according to [1], wherein the total mass of the protein is 4.0% by mass or less relative to the total mass of the sterilized milk beverage. [3] The sterilized milk beverage according to [1] or [2], wherein the ratio of the total mass of the calcium to the total mass of the milk protein is 3.5% by mass or more. [4] The sterilized milk beverage according to any one of [1] to [3], wherein the total mass of the calcium per 100 g of the sterilized milk beverage is 140 mg / 100 g or more. [5] The sterilized milk beverage according to any one of [1] to [4], wherein the acid milk stabilizer includes high methoxyl pectin. [6] The sterilized milk beverage according to any one of [1] to [5], wherein the phosphate content is 0.01% by mass or more relative to the total mass of the sterilized milk beverage, and when the phosphate content is 0.01% by mass or more but less than 0.05% by mass, the acid milk stabilizer content is 0.40% by mass or more, and when the phosphate content is 0.05% by mass or more, the acid milk stabilizer content is 0.30% by mass or more. [7] The sterilized milk beverage according to any one of [1] to [6], wherein the viscosity at 25°C is 300 mPa·s or less. [8] The sterilized milk beverage according to any one of [1] to [7], wherein the median diameter in the volume-based particle size distribution of the particle groups contained in the sterilized milk beverage is 5 μm or less. [9] The sterilized milk beverage according to any one of [1] to [8], wherein the syneresis rate when stored at 25°C for 90 days is 25% or less.

[10] When the sterilized milk beverage is used as a measurement sample liquid and the TSI, which is an index showing the instability of the liquid, is measured by the following measurement method (Z) using a liquid dispersion stability evaluation device, the TSI calculated by the following formula (2) is ｓｌｏｐｅ４８The pasteurized milk beverage according to any one of [1] to [9], wherein the value of is 0.15 or less. Measurement method (Z): (1) Approximately 20 mL of the measurement sample liquid adjusted to 25°C is filled into a glass bottle with an outer diameter of 27 mm, and light with a wavelength of 880 nm is incident from the outside of the glass bottle with the height direction vertical. The intensity of the transmitted light at an angle of 180° and the backscattered light at an angle of 45° relative to the incident direction is measured with a photoreceiver. The measurement is carried out in an atmosphere at 25°C. (2) After a waiting time of 5 minutes, the incident light is scanned from bottom to top in the vertical direction, and the transmitted light and the backscattered light are measured at scan intervals (Δh = 40 μm) (t １ = 0), 4-hour intervals (t ２ = 4, t ３ = 8...), and the total time is 48 hours (t ｍａｘ (3) The lower limit position of the scan area in the vertical direction (z ｍｉｎ ) to the upper limit position (z ｍａｘ ) is the distance to (z ｍａｘ -z ｍｉｎ ), and the number of measurement points in the scan area is N ｈ = (z ｍａｘ -z ｍｉｎ (4) The TSI at 44 hours (t=44) is calculated using the following formula (1): ４４ｈ and TSI at 48 hours (t=48) ４８ｈ is calculated, and TSI is calculated using the following formula (2): ｓｌｏｐｅ４８ In equation (1), BST is a signal obtained by measuring the light intensity, and when the transmitted light intensity is less than 0.2% of the incident light intensity, the backscattered light signal BS is used, and otherwise the transmitted light intensity signal T is used.

[0009]

[0010]

[11] The sterilized milk beverage according to any one of [1] to

[10] , which can be stored at room temperature.

[12] A sterilized milk beverage containing milk protein and calcium, wherein the ratio of the total mass of the calcium to the total mass of the milk protein is 3.5% by mass or more, the pH at 25°C is 5.0 or less, the viscosity at 25°C is 300 mPa s or less, and the syneresis rate after storage at 25°C for 90 days is 25% or less.

[13] The sterilized milk beverage according to

[12] , which can be stored at room temperature.

[14] The sterilized milk beverage according to any one of [1] to

[13] , which is fermented milk that has been sterilized after fermentation.

[15] A method for producing the sterilized milk beverage described in any one of [1] to

[13] above, comprising the steps of: preparing a raw material liquid containing milk protein, calcium, and phosphate and having been primarily sterilized; preparing a stabilizer solution containing an acidic milk stabilizer separately from the raw material liquid; acidifying the raw material liquid to obtain an acidic raw material liquid; mixing the acidic raw material liquid with the stabilizer solution to obtain a mixture; and secondary sterilizing the mixture to obtain the sterilized milk beverage.

[16] A method for producing the sterilized milk beverage described in

[14] above, comprising the steps of: preparing a raw material liquid containing milk protein, calcium, and phosphate and having been primarily sterilized; preparing a stabilizer solution containing an acidic milk stabilizer separately from the raw material liquid; adding a fermenting bacterium to the raw material liquid and fermenting it to obtain a fermented liquid; mixing the fermented liquid with the stabilizer solution to obtain a mixture; and secondary sterilizing the mixture to obtain the sterilized milk beverage.

[0011] In another aspect, the present invention has the following embodiments. [1] A sterilized milk beverage containing milk protein and calcium, wherein the pH at 25°C is 5.0 or less, the milk protein comprises whey protein, the whey protein content is 40% by mass or more relative to the total mass of protein contained in the sterilized milk beverage, and the sterilized milk beverage contains a phosphate and an acid milk stabilizer. [2] The sterilized milk beverage according to [1], wherein the total mass of protein contained in the sterilized milk beverage is 4.0% by mass or less relative to the total mass of the protein contained in the sterilized milk beverage. [3] The sterilized milk beverage according to [1] or [2], wherein the ratio of the total mass of calcium contained in the sterilized milk beverage to the total mass of milk protein contained in the sterilized milk beverage is 3.5% by mass or more. [4] The sterilized milk beverage according to any one of [1] to [3], wherein the total mass of calcium contained in the sterilized milk beverage is 140 mg / 100 g or more per 100 g of the sterilized milk beverage. [5] The sterilized milk beverage according to any one of [1] to [4], wherein the acid milk stabilizer includes high methoxyl pectin. [6] The sterilized milk beverage according to any one of [1] to [5], wherein the content of the phosphate is 0.01% by mass or more relative to the total mass of the sterilized milk beverage, and when the content of the phosphate is 0.01% by mass or more but less than 0.05% by mass, the content of the acid milk stabilizer is 0.40% by mass or more relative to the total mass of the sterilized milk beverage, and when the content of the phosphate is 0.05% by mass or more, the content of the acid milk stabilizer is 0.30% by mass or more relative to the total mass of the sterilized milk beverage. [7] The sterilized milk beverage according to any one of [1] to [6], wherein the viscosity of the sterilized milk beverage at 25°C is 300 mPa s or less. [8] The sterilized milk beverage according to any one of [1] to [7], wherein the median diameter in the volume-based particle size distribution of the particle groups contained in the sterilized milk beverage is 5 μm or less. [9] The sterilized milk beverage according to any one of [1] to [8], wherein the water separation rate when the sterilized milk beverage is stored for 90 days at 25° C. is 25% or less.

[10] When the sterilized milk beverage is used as a measurement sample liquid and the TSI, which is an index showing the instability of the liquid, is measured by the following measurement method (Z) using a liquid dispersion stability evaluation device, the TSI is calculated by the following formula (2): ｓｌｏｐｅ４８The sterilized milk beverage according to any one of [1] to [9], wherein the value of is 0.15 or less. Measurement method (Z): (1) Approximately 20 mL of a measurement sample liquid adjusted to 25°C is filled into a glass bottle with an outer diameter of 27 mm, the glass bottle is held so that its height direction is vertical, and light with a wavelength of 880 nm is incident on the measurement sample liquid from the outside of the glass bottle, and the intensity of the transmitted light at 180° and the backscattered light at 45° relative to the incident direction is measured with a photoreceiver. The measurement is carried out in an atmosphere at 25°C. (2) After a waiting time of 5 minutes, the incident light is scanned from the bottom to the top of the glass bottle in the height direction, while the transmitted light and the backscattered light are measured at scan intervals (Δh) of 40 μm (t １ = 0), 4-hour intervals (t ２ = 4, t ３ = 8...), and the total time is 48 hours (t ｍａｘ (3) The lower limit position (z = 48) of the scanning area in the height direction of the glass bottle is reached. ｍｉｎ ) to the upper limit position (z ｍａｘ ) is the distance to (z ｍａｘ -z ｍｉｎ ), and the number of measurement points in the scan area is N ｈ = (z ｍａｘ -z ｍｉｎ (4) The TSI at 44 hours (t=44) is calculated using the following formula (1): ４４ｈ and TSI at 48 hours (t=48) ４８ｈ is calculated, and TSI is calculated using the following formula (2): ｓｌｏｐｅ４８ In equation (1), BST is a signal obtained by measuring the light intensity, and when the transmitted light intensity is less than 0.2% of the incident light intensity, the backscattered light signal BS is used, and otherwise the transmitted light intensity signal T is used.

[0012]

[0013]

[11] The sterilized milk beverage according to any one of [1] to

[10] , which can be stored at room temperature.

[12] A sterilized milk beverage containing milk protein and calcium, wherein the ratio of the total mass of the calcium to the total mass of the milk protein is 3.5% by mass or more, the pH at 25°C is 5.0 or less, the viscosity at 25°C is 300 mPa s or less, and the syneresis rate after storage at 25°C for 90 days is 25% or less.

[13] The sterilized milk beverage according to

[12] , which can be stored at room temperature.

[14] The sterilized milk beverage according to any one of [1] to

[13] , which is fermented milk that has been sterilized after fermentation.

[15] A method for producing the sterilized milk beverage according to any one of [1] to

[13] above, comprising: preparing a raw material liquid containing milk protein, calcium, and phosphate and subjected to primary sterilization; preparing a stabilizer solution containing an acidic milk stabilizer separately from the raw material liquid; acidifying the raw material liquid to obtain an acidic raw material liquid; mixing the acidic raw material liquid with the stabilizer solution to obtain a mixture; and subjecting the mixture to secondary sterilization to obtain the sterilized milk beverage.

[16] A method for producing the sterilized milk beverage according to

[14] above, comprising: preparing a raw material liquid containing milk protein, calcium, and phosphate and subjected to primary sterilization; preparing a stabilizer solution containing an acidic milk stabilizer separately from the raw material liquid; adding a fermenting bacterium to the raw material liquid and fermenting it to obtain a fermented liquid; mixing the fermented liquid with the stabilizer solution to obtain a mixture; and subjecting the mixture to secondary sterilization to obtain the sterilized milk beverage.

[0014] According to the present invention, a sterilized milk beverage containing milk protein and calcium and having good liquid stability despite having a low pH can be obtained.

[0015] The following definitions apply in this specification. "Room temperature" means a temperature in the range of more than 5°C and not more than 35°C. "Room temperature storable" means that the product can be stored for 90 days or more in an atmosphere of 15°C to 35°C without spoilage or decay. In this specification, the symbol "to" used for a numerical range indicates a numerical range including the lower and upper limits. Furthermore, content rates expressed as percentages in this specification are expressed by mass unless otherwise specified.

[0016] <Measurement Method> The content of components, etc. is measured using the following method.

[0017] The protein content is measured by the Dumas method (also known as the oxygen circulation combustion method). A SUMIGRAPH NC-220F analytical instrument (manufactured by Sumika Chemical Analysis Center Co., Ltd.) can be used. The measurement conditions are as follows: Electric furnace temperature: Reactor 870°C, Reduction furnace: 600°C Oxygen purge: 0.2±0.02 L / min Column temperature: 70±5°C Detector: Detector temperature: 100°C, CURRENT: 160 mA Carrier gas: Helium flow rate 80±5 mL / min at column temperature 70±5°C Constituent reference substance: Aspartic acid Measurement sample amount: 500±100 mg Reference substance amount: 500±100 mg

[0018] The whey protein content (unit: mass %) in the protein is determined as the ratio of the sum of the band intensities of β-lactoglobulin and α-lactalbumin to the sum of the band intensities of α-casein, β-casein, κ-casein, β-lactoglobulin, and α-lactalbumin, as measured by SDS-PAGE (abbreviation for "sodium dodecyl sulfate-polyacrylamide gel electrophoresis").

[0019] The fat content is measured by the Roese-Gottlieb method. Specifically, 3 g of sample is placed in a Majornier tube, and 7 ml of water, 1 drop of phenolphthalein, and 2 ml of ammonia water are added and gently shaken. Then, 10 ml of ethanol, 25 ml of ethyl ether, and 25 ml of petroleum ether are added, with the stopper closed and shaken two or three times after each addition. After centrifuging the Majornier tube, the solvent layer is transferred to a dish and the solvent is evaporated. The residue is fat, and the residue is weighed.

[0020] The moisture content (unit: mass%) is measured using the mixed sand drying method. Specifically, the sample is dried under certain conditions until it reaches a constant weight, and the weight of the dried substance is determined. The calculated loss on drying is used as the moisture content. Specifically, the procedure is as follows: (1) 25 g of refined silica sand and a glass rod are placed in an aluminum weighing tube, and the tube is dried in a dryer until it reaches a constant weight. The tube is then transferred to a desiccator, allowed to cool at room temperature for 30 minutes, and weighed. (2) The tube is tilted to shift the silica sand to one side, and the sample is accurately weighed. The tube is then placed on a table, 5 ml of hot water is added, and the sample is thoroughly and uniformly dispersed with the silica sand using a glass rod. (3) Most of the moisture is evaporated while stirring in a boiling water bath. When the sample becomes smooth, it is placed in a dryer at 99±1°C for 3 hours, allowed to cool in a desiccator for 30 minutes, and weighed. Drying, cooling, and weighing are repeated until a constant weight is reached, and the moisture content is calculated using the following moisture calculation formula. Moisture content (unit: mass%) = loss on drying (unit: g) / sample amount (unit: g) × 100

[0021] The solids concentration (unit: mass %) is calculated from the water content as the content other than the water content. The calculation formula is "100 - water content = solids concentration". The non-fat milk solids content is the value obtained by subtracting the fat (also called milk fat) content from the milk-derived solids (also called milk solids). The calcium (Ca) content is measured by inductively coupled plasma atomic emission spectrometry.

[0022] <Pasteurized Milk Beverage> In this specification, "pasteurized milk beverage" means a milk beverage that satisfies at least one of the following (a) or (b): (a) A milk beverage that has been sterilized so that the total viable count, mold count, and yeast count are all zero per ml and the coliform bacteria test is negative in a microbiological test stipulated in the Food Sanitation Inspection Guidelines in Japan. (b) A milk beverage that has been sterilized so that the total Listeria count and Salmonella count are zero per ml and the coliform bacteria test is negative in a microbiological test stipulated in the Food Sanitation Inspection Guidelines in the CODEX standards. "Milk beverage" means a beverage that uses milk-derived ingredients (hereinafter also referred to as "milk ingredients") and has a milk solids content of 3.0% or more. "Milk" refers to milk derived from a mammal, and examples thereof include milk derived from cows, sheep, or goats. Milk derived from cows (i.e., cow's milk) is preferred.

[0023] The sterilized milk beverage of this embodiment contains milk protein and calcium, and further contains phosphate and an acid milk stabilizer. Proteins other than milk protein may be contained. The milk protein includes at least whey protein. Milk proteins other than whey protein may also be contained. Examples of milk proteins other than whey protein include casein protein.

[0024] [Milk Protein Source] The sterilized milk beverage of this embodiment contains a milk protein source containing whey protein (excluding the calcium source described below). Examples of milk protein sources containing whey protein include raw milk, skim milk, concentrated skim milk, skim milk powder, whey powder, WPC (abbreviation for whey protein concentrate), WPI (abbreviation for whey protein isolate), and heat-denatured WPC. Of these, heat-denatured WPC is preferred because it is easy to achieve liquid stability and low viscosity. Heat-denatured WPC is obtained by heating whey protein concentrate to cause it to aggregate, and then applying shear force to granulate it, and is available as a commercially available product.

[0025] The whey protein content (hereinafter also referred to as "whey / total protein") relative to the total mass of protein contained in the sterilized milk beverage of this embodiment (hereinafter also referred to as "total protein") is 40% by mass or more, preferably 50% by mass or more, more preferably 60% by mass or more, even more preferably 70% by mass or more, even more preferably 80% by mass or more, and even more preferably 90% by mass or more. It may even be 100% by mass. When the whey / total protein ratio is equal to or greater than the lower limit of the above range, the liquid stability is excellent. Specifically, aggregation and thickening due to heat sterilization are easily suppressed, and syneresis and sedimentation during storage are less likely to occur.

[0026] The total protein content relative to the total mass of the sterilized milk beverage is preferably 4.0% by mass or less, more preferably 3.5% by mass or less, even more preferably 3.1% by mass or less, and particularly preferably 2.5% by mass or less. The upper limit of the total protein content may be 2.0% by mass or less, or may be 1.0% by mass or less. The lower limit of the total protein content is not particularly limited, but may be, for example, 0.1%, 0.3%, 0.5%, 0.7%, or 1.1% by mass. A total protein content of less than the upper limit of the above range provides excellent liquid stability. Specifically, aggregation and thickening due to heat sterilization are easily suppressed, and syneresis and sedimentation during storage are less likely to occur. The total protein content relative to the total mass of the sterilized milk beverage is, for example, preferably 0.1 to 4.0% by mass, more preferably 0.7 to 3.1% by mass, and particularly preferably 1.1 to 2.5% by mass.

[0027] The milk protein content relative to the total protein of the sterilized milk beverage (hereinafter also referred to as "milk protein / total protein") is preferably 40% by mass or more, more preferably 60% by mass or more, and even more preferably 80% by mass or more. It may be 100% by mass. When the milk protein / total protein ratio is equal to or greater than the lower limit of the above range, aggregation and thickening due to heat sterilization are easily suppressed, syneresis and sedimentation during storage are less likely to occur, and protein with an excellent amino acid balance can be supplied.

[0028] [Calcium Source] The sterilized milk beverage of this embodiment preferably contains a calcium source containing 5.0% by mass or more of calcium (Ca). Examples of calcium sources include milk calcium concentrate, calcium phosphate, calcium citrate, and calcium carbonate. In terms of digestibility and absorbability, the calcium source is preferably derived from milk, and milk calcium concentrate is more preferred. Milk calcium concentrate is a milk-derived composition in which the calcium concentration is increased by separating and removing fat, protein, lactose, etc. from milk. It is commercially available.

[0029] The ratio of the total mass of calcium to the total mass of milk protein (hereinafter also referred to as "total calcium / milk protein") is preferably 3.5% by mass or more, more preferably 4.0% by mass or more, more preferably 5.0% by mass or more, more preferably 6.0% by mass or more, more preferably 7.0% by mass or more, and even more preferably 8.0% by mass or more. In general, the calcium content per gram of milk protein is approximately 33.3 mg (i.e., 3.33% by mass). The pasteurized milk beverage of this embodiment is preferably a calcium-fortified milk beverage to which calcium has been added. If the total calcium / milk protein ratio is above the above-mentioned lower limit, the liquid stability is likely to decrease due to the calcium fortification, and this is preferable in that the application of the present invention is more effective. The upper limit of the total calcium / milk protein ratio is not particularly limited, but may be, for example, 57% by mass, 36% by mass, or 26% by mass.

[0030] The total mass of calcium per 100 g of the pasteurized milk beverage (hereinafter also referred to as "total calcium") is preferably 140 mg / 100 g or more, more preferably 180 mg / 100 g or more, more preferably 200 mg / 100 g or more, more preferably 230 mg / 100 g or more, more preferably 250 mg / 100 g or more, more preferably 270 mg / 100 g or more, more preferably 290 mg / 100 g or more, and even more preferably 310 mg / 100 g or more. If the total calcium is above the lower limit, the liquid stability is likely to decrease, which is preferable in that the application of the present invention is more effective. The upper limit of the total calcium is not particularly limited, but may be 400 mg / 100 g, 350 mg / 100 g, 314 mg / 100 g, 290 mg / 100 g, 250 mg / 100 g, 230 mg / 100 g, 200 mg / 100 g, or 180 mg / 100 g from the viewpoint of ensuring liquid stability.

[0031] In the sterilized milk beverage, the total calcium / milk protein ratio is preferably 3.5% by mass or more and the total calcium is 140 to 400 mg / 100 g, more preferably 4.0% by mass or more and the total calcium is 180 to 314 mg / 100 g, and even more preferably 4.0% by mass or more and the total calcium is 180 to 250 mg / 100 g.

[0032] When the sterilized milk beverage is a calcium-fortified milk beverage, the total mass of additionally added calcium (hereinafter also referred to as "added calcium") per 100 g of the sterilized milk beverage is preferably 20 mg / 100 g or more, more preferably 60 mg / 100 g or more, more preferably 110 mg / 100 g or more, and even more preferably 180 mg / 100 g or more. If the total calcium is above the above lower limit, the liquid stability is likely to decrease, which is preferable in that the application of the present invention is more effective. The upper limit of the total mass of added calcium per 100 g of the sterilized milk beverage is not particularly limited, but from the viewpoint of ensuring liquid stability, it may be, for example, 400 mg / 100 g, 350 mg / 100 g, or 314 mg / 100 g.

[0033] [Phosphate and Acid Milk Stabilizer] In this embodiment, the phosphate and acid milk stabilizer contribute to improving the liquid stability. Examples of phosphate include sodium hexametaphosphate, sodium ultraphosphate, sodium polyphosphate, potassium dihydrogen phosphate, and tetrapotassium pyrophosphate. In particular, from the viewpoint of liquid stability, it is preferable that the phosphate contains sodium hexametaphosphate. For example, it is preferable that 20% by mass or more, preferably 50% by mass or more of the total mass of the phosphate is sodium hexametaphosphate.

[0034] As used herein, "acid milk stabilizer" refers to a thickening polysaccharide that inhibits protein precipitation and aggregation in an acidic range and stabilizes proteins. Specific examples include high methoxyl pectin, soybean polysaccharides, and carboxymethyl cellulose. In particular, from the viewpoint of liquid stability, it is preferable that the acid milk stabilizer contains high methoxyl pectin. For example, it is preferable that high methoxyl pectin accounts for 20% by mass or more, and preferably 50% by mass or more, of the total mass of the acid milk stabilizer.

[0035] The content of phosphate is preferably 0.01% by mass or more, more preferably 0.05% by mass or more, relative to the total mass of the sterilized milk beverage. The upper limit is not particularly limited, but in terms of the flavor presented, it is preferably 0.5% by mass or less, more preferably 0.3% by mass or less. The content of sour milk stabilizer is preferably 0.30% by mass or more, more preferably 0.40% by mass or more, relative to the total mass of the sterilized milk beverage. The upper limit is not particularly limited, but in terms of easily maintaining low viscosity, it is preferably 1.00% by mass or less, more preferably 0.80% by mass or less. When the content of phosphate is 0.01% by mass or more and less than 0.05% by mass, relative to the total mass of the sterilized milk beverage, the content of sour milk stabilizer is preferably 0.40% by mass or more, more preferably 0.45% by mass or more, and even more preferably 0.50% by mass or more. When the phosphate content is 0.05% by mass or more relative to the total mass of the sterilized milk beverage, the content of the sour milk stabilizer is preferably 0.30% by mass or more, more preferably 0.40% by mass or more, and even more preferably 0.50% by mass or more. When the contents of the phosphate and the sour milk stabilizer are each equal to or greater than the lower limit of the above range, the effect of improving the liquid stability is excellent.

[0036] [Other Components] The sterilized milk beverage of the present embodiment may contain other components in addition to the whey protein-containing milk protein source, calcium source, phosphate, acid milk stabilizer, and water. Examples of other components include sugars, sweeteners, acidulants, casein hydrolysates, animal fats, vegetable fats, flavorings, pH adjusters, vitamins, minerals, dietary fiber, fruit juice, antioxidants, coloring agents, etc.

[0037] The sterilized milk beverage of this embodiment is acidic. For example, it may be a milk beverage acidified by adding an acidulant or fruit juice, or it may be fermented milk acidified by fermentation. The pH of the sterilized milk beverage at 25°C is 5.0 or less, preferably 3.5 to 4.5, and more preferably 3.7 to 4.3. If the pH of the sterilized milk beverage is below the upper limit and above the lower limit of the above range, it will not only exhibit a moderate sourness as a sour milk beverage, but will also maximize the effect of the sour milk stabilizer, improving liquid stability, which is preferable.

[0038] The sterilized milk beverage of this embodiment is preferably fermented milk (also referred to as sterilized fermented milk) that has been sterilized after fermentation. Sterilization in a state where the pH has been lowered by fermentation tends to reduce liquid stability, so the application of the present invention is highly effective. Fermented milk in this specification refers to "a product obtained by fermenting milk or milk containing an equivalent or higher non-fat milk solids content with lactic acid bacteria or yeast to form a paste or liquid, or a product obtained by freezing these," as defined in the "Ministerial Ordinance on Compositional Standards, etc. of Milk and Dairy Products" in Japan. The non-fat milk solids content is 8.0% or more, as specified in the component standards of the ministerial ordinance. Sterilized fermented milk in this specification refers to fermented milk that has been heated at 75°C or higher for 15 minutes after fermentation, or heat-sterilized using a method that has an equivalent or higher sterilization effect, as defined in the "Ministerial Ordinance on Compositional Standards, etc. of Milk and Dairy Products" in Japan. Sterilized fermented milk beverages, which are sterilized fermented milk, contain killed fermentation bacteria.

[0039] <Method for producing sterilized milk beverage> The sterilized milk beverage of this embodiment can be produced by a method including the steps of preparing a raw material liquid containing milk protein, calcium, and phosphate and subjected to primary sterilization (also referred to as the first step), preparing a stabilizer liquid containing an acidic milk stabilizer separately from the raw material liquid (also referred to as the second step), acidifying the raw material liquid to obtain an acidic raw material liquid (also referred to as the acidification step), mixing the acidic raw material liquid and the stabilizer liquid to obtain a mixture (also referred to as the mixing step), and secondarily sterilizing the mixture to obtain a sterilized milk beverage (also referred to as the secondary sterilization step). When the sterilized milk beverage is sterilized fermented milk, in the acidification step, fermentation bacteria are added to the raw material liquid and fermented to obtain a fermentation liquid, and in the mixing step, the fermentation liquid and the stabilizer liquid are mixed. In the manufacturing method of this embodiment, a raw material liquid containing milk protein, calcium, and phosphate is primarily sterilized without containing an acid milk stabilizer, then acidified after the primary sterilization, and after acidification, an acid milk stabilizer is added and the liquid is secondary sterilized. Therefore, this method is suitable for manufacturing a sterilized milk beverage that contains milk protein and calcium and has a low pH, but in which protein aggregation and thickening are suppressed.

[0040] [First Step] The raw material liquid can be prepared by mixing and dissolving a whey protein-containing milk protein source, a calcium source, phosphate, water, and other ingredients as needed, followed by heat sterilization (also referred to as primary sterilization). The raw material liquid does not contain an acid milk stabilizer. The pH of the raw material liquid at 25°C is preferably greater than 5.5, more preferably 6.0 or higher. Heating may be performed when dissolving the raw materials. The liquid temperature when dissolving the raw materials is preferably, for example, 10 to 90°C. Homogenization may be performed before heat sterilization. Homogenization conditions are preferably, for example, a liquid temperature of 55 to 85°C and a homogenization pressure of 10 to 25 MPa. Heat sterilization conditions are preferably, for example, 90 to 145°C for 15 minutes to 2 seconds. After heat sterilization, the raw material liquid is preferably cooled, for example, to 25 to 45°C.

[0041] [Second Step] The stabilizer solution can be prepared by mixing and dissolving the sour milk stabilizer in water. The stabilizer solution may contain other ingredients except for the milk protein source, calcium source, and phosphate. The stabilizer solution may or may not include a heat sterilization step. If heat sterilization is performed, the conditions are preferably, for example, 75 to 145°C for 15 minutes to 2 seconds. After heat sterilization, the stabilizer solution is preferably cooled to, for example, 5 to 30°C.

[0042] [Acidification Step] The raw material liquid obtained in the first step may be acidified by adding an acid component such as an acidulant or fruit juice as another component, or by adding a fermenting bacterium to the raw material liquid obtained in the first step and fermenting it. Examples of acidulants include citric acid and lactic acid. The pH at 25°C of both the acidic raw material liquid obtained by adding an acid component and the fermented liquid obtained by fermentation is preferably 3.0 to 5.0, more preferably 3.8 to 4.5.

[0043] When fermenting a raw material liquid, it is preferable to use at least lactic acid bacteria as the fermenting bacteria. Two or more types of lactic acid bacteria may be combined. In addition to lactic acid bacteria, one or more known fermenting bacteria, such as bifidobacteria and yeast, may be used in combination. It is preferable to use a lactic acid bacteria starter as the fermenting bacteria. For example, it is preferable to use one or more lactic acid bacteria starters commonly used in yogurt production, such as Lactobacillus bulgaricus (L. bulgaricus), Lactococcus lactis (L. lactis), and Streptococcus thermophilus (S. thermophilus). Lactic acid bacteria starters are commercially available.

[0044] In the fermentation step, fermentation bacteria are added to the raw material liquid, and the liquid is fermented at a predetermined pH to obtain a fermented liquid. It is preferable to adjust the temperature of the raw material liquid to a predetermined fermentation temperature before adding the fermentation bacteria. For example, when using the lactic acid bacteria starters exemplified above as fermentation bacteria, the fermentation temperature is preferably 25 to 45°C, more preferably 35 to 43°C. Since acid is produced during fermentation by lactic acid bacteria, the pH of the raw material liquid decreases over time after fermentation begins. The pH of the raw material liquid in the fermentation step can be adjusted by the type of fermentation bacteria, the amount added, and the fermentation time. Once the pH reaches a target value (also referred to as the target pH), the curd is pulverized by stirring or homogenization to obtain a fermented liquid.

[0045] [Mixing step] Next, the acidic raw material liquid or fermentation liquid obtained in the acidification step is mixed with the stabilizer liquid obtained in the second step to obtain a mixture. The mixing ratio is preferably set so that the composition of the mixture will be the composition of the desired sterilized milk beverage.

[0046] [Secondary Sterilization Step] Next, the mixture obtained in the mixing step is subjected to secondary sterilization to obtain the desired sterilized milk beverage. Heat sterilization conditions are preferably, for example, 80 to 112°C for 5 minutes to 2 seconds. Homogenization treatment may be performed before or after heat sterilization. Homogenization conditions are preferably, for example, a liquid temperature of 20 to 100°C and a homogenization pressure of 10 to 25 MPa. After secondary sterilization, the mixture is preferably cooled to, for example, 15 to 40°C.

[0047] [Filling process] A container-packed sterilized milk beverage is obtained by filling and sealing the secondarily sterilized sterilized milk beverage into a container (also referred to as the filling process). In the filling process, the sterilized milk beverage is aseptically filled into a container and sealed to obtain a container-packed sterilized milk beverage that can be stored at room temperature. As a method for aseptically filling into a container, a known aseptic filling method can be used, such as a method of filling and sealing a sterilized container in a sterile environment where the number of viable bacteria is controlled, such as a sterile room.

[0048] [Cooling step] When producing a packaged sterilized milk beverage that can be stored at room temperature, it is preferable to provide a step (also referred to as a cooling step) of cooling the packaged sterilized milk beverage to 1 to 10°C after filling and sealing it into a container and before storing it at room temperature. For example, the packaged sterilized milk beverage is cooled by being placed in a refrigerator with an internal temperature of 1 to 10°C. The cooling step contributes to improving the stability of the physical properties of the sterilized milk beverage. The cooling time from being placed in the refrigerator until being taken out may be at least the time required for the liquid temperature of the sterilized milk beverage to reach 10°C or below. For example, 10 minutes or more is preferable, 4 hours or more is more preferable, and 24 hours or more is even more preferable. The upper limit of the cooling time is not particularly limited. The liquid temperature of the sterilized milk beverage in the cooling step is preferably 1 to 8°C, more preferably 1 to 5°C.

[0049] According to this embodiment, thickening during secondary sterilization can be suppressed, and a sterilized milk beverage can be obtained having a viscosity at 25°C of 300 mPa·s or less, preferably 200 mPa·s or less, more preferably 150 mPa·s or less, and even more preferably 100 mPa·s or less. The viscosity in this specification is a value measured using the method described in the Examples below. If the viscosity at 25°C is below the above upper limit, a refreshing and pleasant drinking experience is likely to be obtained. The lower limit of the viscosity of the sterilized milk beverage at 25°C is not particularly limited, but may be, for example, 5 mPa·s, 10 mPa·s, or 15 mPa·s.

[0050] According to this embodiment, aggregation during secondary sterilization can be suppressed, and a sterilized milk beverage can be obtained in which the median diameter of the particle groups contained in the sterilized milk beverage in the volume-based particle size distribution is 5 μm or less, preferably 3 μm or less, and more preferably 2 μm or less. The median diameter in this specification refers to the particle diameter at the 50% point on the cumulative volume distribution curve measured using a laser diffraction / scattering particle size distribution analyzer, i.e., the volume-based cumulative 50% diameter (d50). The smaller the median diameter measured using a sterilized milk beverage as the measurement subject, the more suppressed the aggregation of milk proteins and the more stable the beverage is. A median diameter of 5 μm or less results in a smooth texture without any roughness. The lower limit of the median diameter of the sterilized milk beverage is not particularly limited, but may be, for example, 0.2 μm, 0.3 μm, 0.5 μm, or 0.7 μm.

[0051] According to this embodiment, syneresis during storage can be suppressed, and a sterilized milk beverage can be obtained in which the syneresis rate after storage at 25° C. for 90 days is 25% or less, preferably 5% or less, more preferably 4% or less, more preferably 3% or less, and even more preferably 2% or less. The syneresis rate may be 0. The syneresis rate in this specification is a value obtained by the measurement method described in the Examples below.

[0052] According to this embodiment, the liquid stability of the sterilized milk beverage can be improved, and TSI ｓｌｏｐｅ４８ It is possible to obtain a pasteurized milk beverage having a TSI value of 0.15 or less, preferably 0.027 or less, more preferably 0.020 or less, more preferably 0.015 or less, and even more preferably 0.010 or less. ｓｌｏｐｅ４８ The value of may be 0. The Turbiscan Stability Index (TSI) is an index that can evaluate the stability of a dispersion liquid, as described in Food Science and Technology Research, 26(6), 863-873, 2020. ｓｌｏｐｅ４８ The smaller the value of TSI, the smaller the morphological changes such as sedimentation and water separation during storage, and the more stable the product. ｓｌｏｐｅ４８ is a value obtained by the following measurement method (Z) using a sterilized milk beverage as a measurement sample liquid and an in-liquid dispersion stability evaluation device.

[0053] Measurement method (Z) (1) Approximately 20 mL of the measurement sample liquid adjusted to 25°C is filled into a glass bottle with an outer diameter of 27 mm, the glass bottle is held so that its height direction is vertical, light with a wavelength of 880 nm is incident on the measurement sample liquid from the outside of the glass bottle, and the intensity of the transmitted light at 180° and the backscattered light at 45° relative to the incident direction is measured with a photodetector. The measurement is carried out in an atmosphere at 25°C. (2) After a waiting time of 5 minutes, the incident light is scanned from the bottom to the top of the glass bottle in the height direction, while the transmitted light and the backscattered light are measured at scan intervals (Δh) of 40 μm (t １ = 0), 4-hour intervals (t ２ = 4, t ３ = 8...), and the total time is 48 hours (tｍａｘ (3) The lower limit position (z = 48) of the scanning area in the height direction of the glass bottle is reached. ｍｉｎ ) to the upper limit position (z ｍａｘ ) is the distance to (z ｍａｘ -z ｍｉｎ ), and the number of measurement points in the scan area is N ｈ = (z ｍａｘ -z ｍｉｎ (4) The TSI at 44 hours (t=44) is calculated using the following formula (1): ４４ｈ and TSI at 48 hours (t=48) ４８ｈ is calculated, and TSI is calculated using the following formula (2): ｓｌｏｐｅ４８ In equation (1), BST is a signal obtained by measuring the light intensity, and when the transmitted light intensity is less than 0.2% of the incident light intensity, the backscattered light signal BS is used, and otherwise the transmitted light intensity signal T is used.

[0054]

[0055] According to this embodiment, the sterilized milk beverage can be stored at room temperature, and can be stored in an atmosphere of 15°C to 35°C for a period of 90 days or more, preferably 120 days or more, and more preferably 180 days or more without spoilage or decay.

[0056] The present invention has the following aspects. [1] A sterilized milk beverage containing milk protein and calcium, the sterilized milk beverage having a pH of 3.5 to 5.0 at 25°C, the milk protein comprising whey protein, the whey protein content being 40 to 100% by mass relative to the total mass of protein contained in the sterilized milk beverage, and containing a phosphate and an acid milk stabilizer. [2] The sterilized milk beverage according to [1], wherein the total mass of protein contained in the sterilized milk beverage is 0.1 to 4.0% by mass relative to the total mass of the sterilized milk beverage. [3] The sterilized milk beverage according to [1] or [2], wherein the ratio of the total mass of calcium contained in the sterilized milk beverage to the total mass of milk protein contained in the sterilized milk beverage is 3.5 to 57% by mass. [4] The sterilized milk beverage according to any one of [1] to [3], wherein the total mass of calcium contained in the sterilized milk beverage is 140 to 400 mg / 100 g of the sterilized milk beverage. [5] The sterilized milk beverage according to any one of [1] to [4], wherein the acidified milk stabilizer comprises high methoxyl pectin, and the proportion of high methoxyl pectin relative to the total mass of the acidified milk stabilizer is 20 to 100% by mass. [6] The sterilized milk beverage according to any one of [1] to [5], wherein the content of the phosphate is 0.01% by mass or more but less than 0.05% by mass relative to the total mass of the sterilized milk beverage, and the content of the acidified milk stabilizer is 0.40 to 1.0% by mass relative to the total mass of the sterilized milk beverage. [7] The sterilized milk beverage according to any one of [1] to [5], wherein the content of the phosphate is 0.05 to 5.0% by mass relative to the total mass of the sterilized milk beverage, and the content of the acidified milk stabilizer is 0.30 to 1.0% by mass relative to the total mass of the sterilized milk beverage. [8] The sterilized milk beverage according to any one of [1] to [7], wherein the viscosity of the sterilized milk beverage at 25°C is 5 to 300 mPa·s. [9] The sterilized milk beverage according to any one of [1] to [8], wherein the median diameter of the particle group contained in the sterilized milk beverage in a volume-based particle size distribution is 0.3 to 5 μm.

[10] The sterilized milk beverage according to any one of [1] to [9], wherein the syneresis rate when the sterilized milk beverage is stored at 25°C for 90 days is 0 to 25%.

[11] When the sterilized milk beverage is used as a measurement sample liquid and the TSI, which is an index showing the instability of the liquid, is measured by the measurement method (Z) using a liquid dispersion stability evaluation device, the TSI is calculated using the formula (2). ｓｌｏｐｅ４８

[12] The sterilized milk beverage according to any one of [1] to

[11] , wherein the ratio of the total mass of calcium contained in the sterilized milk beverage to the total mass of milk protein contained in the sterilized milk beverage is 3.5% by mass or more and less than 4.0% by mass, and the total mass of calcium contained in the sterilized milk beverage per 100 g of the sterilized milk beverage is 140 to 400 mg / 100 g.

[13] The sterilized milk beverage according to any one of [1] to

[11] , wherein the ratio of the total mass of calcium contained in the sterilized milk beverage to the total mass of milk protein contained in the sterilized milk beverage is 4.0 to 36% by mass, and the total mass of calcium contained in the sterilized milk beverage per 100 g of the sterilized milk beverage is 180 to 314 mg / 100 g.

[14] The sterilized milk beverage according to any one of [1] to

[13] , wherein the phosphate comprises sodium hexametaphosphate, and the ratio of the sodium hexametaphosphate to the total mass of the phosphate is 20 to 100% by mass.

[15] The sterilized milk beverage according to any one of [1] to

[14] , wherein the milk protein content is 40 to 100% by mass relative to the total mass of protein contained in the sterilized milk beverage.

[16] A sterilized milk beverage containing milk protein and calcium, wherein the ratio of the total mass of the calcium to the total mass of the milk protein is 3.5 to 26% by mass, the pH at 25°C is 3.5 to 5.0, the viscosity at 25°C is 10 to 300 mPa s, and the syneresis rate after storage at 25°C for 90 days is 0 to 25%.

[17] The sterilized milk beverage according to

[16] , wherein the milk protein content is 40 to 100% by mass relative to the total mass of protein contained in the sterilized milk beverage.

[18] The pasteurized milk beverage according to

[16] or

[17] , which can be stored at room temperature.

[19] The pasteurized milk beverage according to any one of [1] to

[18] , which is fermented milk that has been pasteurized after fermentation.

[0057] The present invention will be described in more detail below using examples, but the present invention is not limited to these examples. In the following, the unit of content, "%", is "% by mass" unless otherwise specified.

[0058] <Measurement Method> The following measurement method was used. [Method for Measuring Median Diameter] Using a pasteurized milk beverage as a sample, a laser diffraction / scattering particle size distribution analyzer (HORIBA product name: Partica LA-950V2) was used to measure the particle size distribution under the following measurement conditions. In detail, first, a flow cell attached to the device was connected, and the sample was dropped into a circulating dispersion medium, which was then circulated and stirred to prepare the sample. When the sample transmittance reached a predetermined value, the device was operated to capture laser diffraction / scattering data. A particle size distribution was obtained based on the captured data, and the volume-based median diameter in the obtained particle size distribution was calculated. (Measurement conditions: wet) Dispersion medium: water. Sample refractive index: 1.600-0.000. Dispersion method: no ultrasonic irradiation, no surfactant or dispersant was used. Circulation speed: scale "5" (flow rate 2.3 L / min, motor rotation speed 1160 rpm) Stirring speed: scale "2" Sample transmittance: 85.0±5.0%

[0059] [Method of Measuring Viscosity] The viscosity was measured using a Brookfield viscometer with a No. 2 rotor at a rotation speed of 60 rpm, and was measured 10 seconds after the start of the measurement (unit: mPa·s).

[0060] [TSI ｓｌｏｐｅ４８ Measurement method for TSI] ｓｌｏｐｅ４８ The in-liquid dispersion stability evaluation device used was "Turbiscan Tower" manufactured by Formulation Inc.

[0061] [Method for measuring syneresis rate] 45 mL of sample was filled into a 50 mL graduated sterile plastic tube and left to stand at 25° C. for 90 days, and the volume of the transparent syneresis layer formed on the top was measured visually. The volume of the syneresis layer obtained by measurement was divided by the total volume of the sample to calculate the volume ratio of the syneresis layer, which was used as the syneresis rate.

[0062] <Ingredients> The following ingredients were used. Skim milk powder: manufactured by Morinaga Milk Industry Co., Ltd., non-fat milk solids 95.2%, fat 1.0%, protein 34.0%, whey protein 6.8%, calcium 1.2%. Whey powder: manufactured by Morinaga Milk Industry Co., Ltd., non-fat milk solids 95.0%, fat 1.0%, protein 12.5%, whey protein 12.5%, calcium 0.5%. Thermally denatured WPC (1): Arla Foods Ingredients, product name "Nutrilac YO-8075", non-fat milk solids 86.0%, fat 6.3%, protein 80.3%, whey protein 80.3%, calcium 0.4%, powder. Heat-denatured WPC (2): Arla Foods Ingredients, product name "Nutrilac CH-4560," nonfat milk solids 88.9%, fat 2.3%, protein 43.5%, whey protein 43.5%, calcium 1.4%, powder. Lactose: Milei GmbH, edible grade, nonfat milk solids 98.0%, fat 1.0%, protein 2.0%, whey protein 0.4%, calcium 0%, powder. Milk calcium concentrate: Morinaga Milk Industry, product name "Milk Ca-28EX," nonfat milk solids 87.5%, fat 0.1%, protein 3.1%, whey protein 3.1%, calcium 30.0%, powder. Phosphate (1): Sodium hexametaphosphate, Taihei Chemical Industry, powder. Lactic acid bacteria starter: Danisco product name "YO-MIX (registered trademark) 505". Sour milk stabilizer (1): high methoxyl pectin, San-Ei Gen FFI product name "SM-MN-2779", powder.

[0063] <Examples 1 to 25> Sterilized milk beverages, which are fermented milk that has been sterilized after fermentation, were produced with the formulations shown in Tables 1 to 5. Examples 1 to 3 and 8 are comparative examples, and Examples 4 to 7 and 9 to 25 are working examples.

[0064] First, the raw materials other than the lactic acid bacteria starter were mixed in a mixer to prepare a mixed liquid according to the fermentation liquid composition shown in the table. The temperature of the mixed liquid was 70°C. Next, the temperature was raised and homogenized using a homogenizer. The homogenization conditions were a temperature of 85°C, a pressure of 15 MPa for 2 seconds. The 85°C mixed liquid obtained after the homogenization process was subjected to heat sterilization (also known as primary sterilization) in a batch sterilizer at 90°C for 10 minutes, and then the temperature was lowered to 43°C to obtain a raw material liquid. The lactic acid bacteria starter was added to the cooled raw material liquid, and the liquid was fermented in a tank at 41-45°C until the desired pH was reached. The temperature was lowered to 10°C to terminate the fermentation. The liquid after fermentation was used as a fermentation liquid. Separately, a sour milk stabilizer and water were mixed according to the stabilizer liquid composition shown in the table to obtain a stabilizer liquid. Next, the fermented liquid and stabilizer liquid were mixed according to the milk beverage formulation shown in the table, heated to 40°C in a tubular heat exchanger, and homogenized at a pressure of 15 MPa using a homogenizer to obtain a milk beverage in which the milk protein curds were crushed (i.e., a mixture of fermented milk and stabilizer liquid). The resulting 40°C milk beverage was heat-sterilized (also known as secondary sterilization) at 90°C for 30 seconds, and then cooled to 30°C to obtain a sterilized milk beverage. The resulting sterilized milk beverage was aseptically filled into containers and sealed to obtain a container-packed sterilized milk beverage (i.e., drinkable yogurt) that can be stored at room temperature. The filling temperature was 30°C, and the filling volume was 45 mL. After the filling process was completed, the beverage was transferred to a room temperature environment of 25°C and stored.

[0065] The container-packed sterilized milk beverage stored at room temperature for one day was used as the measurement object, and the median diameter of the sterilized milk beverage was measured by the above-mentioned method. The container-packed sterilized milk beverage stored at room temperature for one day was used as the measurement object, and the viscosity of the sterilized milk beverage was measured by the above-mentioned method. The container-packed sterilized milk beverage stored at room temperature for one day was used as the measurement object, and the TSI of the sterilized milk beverage was measured by the above-mentioned method. ｓｌｏｐｅ４８ was measured by the above method. The container-packed sterilized milk beverage stored at room temperature for 90 days was used as the measurement subject, and the syneresis rate was measured by the above method. The container-packed sterilized milk beverage stored at room temperature for 1 day was used as the measurement subject, and the pH at 25°C was measured. These results are shown in the table.

[0066]

[0067]

[0068]

[0069]

[0070]

[0071] As shown in the results in the table, the sterilized milk beverages of Examples 4 to 7 and 9 to 25 were calcium-fortified and sterilized by heat sterilization at a low pH, but had a small median diameter and low viscosity, and aggregation and thickening due to heat sterilization were suppressed. ｓｌｏｐｅ４８ The values ​​of β-glucan were small, and syneresis was minimal even when stored at room temperature for a long period of time, resulting in excellent liquid stability during storage. On the other hand, Examples 2 and 8, which contained small amounts of whey protein, and Example 1, which contained small amounts of whey protein and no phosphate, showed significant thickening and a large median diameter. Comparing Examples 2 and 8, it is believed that the use of thermally denatured whey protein in Example 8 reduced the viscosity compared to Example 2, thereby promoting syneresis. Furthermore, Example 3, which contained neither phosphate nor acid milk stabilizer, showed poor liquid stability during storage and showed significant syneresis when stored at room temperature for a long period of time.

[0072] According to the present invention, a sterilized milk beverage containing milk protein and calcium and having good liquid stability despite having a low pH can be obtained.

Claims

1. A sterilized milk beverage containing milk protein and calcium, wherein the pH at 25°C is 5.0 or less, the milk protein comprises whey protein, the whey protein content is 40% by mass or more relative to the total mass of protein contained in the sterilized milk beverage, and the sterilized milk beverage contains a phosphate and an acid milk stabilizer.

2. The pasteurized milk beverage according to claim 1, wherein the total mass of protein contained in the pasteurized milk beverage is 4.0 mass% or less relative to the total mass of the pasteurized milk beverage.

3. The pasteurized milk beverage according to claim 1, wherein the ratio of the total mass of calcium contained in the pasteurized milk beverage to the total mass of milk protein contained in the pasteurized milk beverage is 3.5 mass% or more.

4. The pasteurized milk beverage according to claim 1, wherein the total mass of calcium contained in the pasteurized milk beverage per 100 g of the pasteurized milk beverage is 140 mg / 100 g or more.

5. The pasteurized milk beverage of claim 1, wherein the acid milk stabilizer comprises high methoxyl pectin.

6. The pasteurized milk beverage according to claim 1, wherein the content of the phosphate is 0.01% by mass or more relative to the total mass of the pasteurized milk beverage, and when the content of the phosphate is 0.01% by mass or more and less than 0.05% by mass, the content of the sour milk stabilizer is 0.40% by mass or more relative to the total mass of the pasteurized milk beverage, and when the content of the phosphate is 0.05% by mass or more, the content of the sour milk stabilizer is 0.30% by mass or more relative to the total mass of the pasteurized milk beverage.

7. The pasteurized milk beverage according to claim 1, wherein the viscosity of the pasteurized milk beverage at 25°C is 300 mPa·s or less.

8. The pasteurized milk beverage according to claim 1, wherein the median diameter in the volume-based particle size distribution of the particles contained in the pasteurized milk beverage is 5 μm or less.

9. The pasteurized milk beverage according to claim 1, wherein the water separation rate of the pasteurized milk beverage when stored at 25° C. for 90 days is 25% or less.

10. When the pasteurized milk beverage is used as a measurement sample liquid and the TSI, which is an index showing the instability of the liquid, is measured by the following measurement method (Z) using a liquid dispersion stability evaluation device, the TSI calculated by the following formula (2) is ｓｌｏｐｅ４８ The pasteurized milk beverage according to claim 1, wherein the value of is 0.15 or less. Measurement method (Z) (1) About 20 mL of the measurement sample liquid adjusted to 25°C is filled into a glass bottle with an outer diameter of 27 mm, the glass bottle is held so that its height direction is vertical, light with a wavelength of 880 nm is incident on the measurement sample liquid from the outside of the glass bottle, and the intensity of the transmitted light at 180° and the backscattered light at 45° with respect to the incident direction is measured with a light receiver. The measurement is performed in an atmosphere at 25°C. (2) After a waiting time of 5 minutes, the incident light is scanned from the bottom to the top of the glass bottle in the height direction, and the transmitted light and the backscattered light are measured at scan intervals (Δh) of 40 μm (t １ = 0), and at 4-hour intervals (t ２ = 4, t ３ = 8...), and the total time is 48 hours (t ｍａｘ (3) The lower limit position (z = 48) of the scan area in the height direction of the glass bottle is reached. ｍｉｎ ) to the upper limit position (z ｍａｘ ) is the distance to ｍａｘ -z ｍｉｎ ), and the number of measurement points in the scan area is N ｈ = (z ｍａｘ -z ｍｉｎ (4) The TSI at 44 hours (t=44) is calculated using the following formula (1): ４４ｈ and TSI at 48 hours (t=48) ４８ｈ and calculate TSI by the following formula (2): ｓｌｏｐｅ４８ In formula (1), BST is a signal obtained by measuring the light intensity, and when the transmitted light intensity is smaller than 0.2% of the incident light intensity, the backscattered light signal BS is used, and otherwise the transmitted light intensity signal T is used.

11. The pasteurized milk beverage according to claim 1, which is shelf stable.

12. A pasteurized milk beverage containing milk protein and calcium, wherein the ratio of the total mass of the calcium to the total mass of the milk protein is 3.5% by mass or more, the pH at 25°C is 5.0 or less, the viscosity at 25°C is 300 mPa·s or less, and the syneresis rate when stored at 25°C for 90 days is 25% or less.

13. The pasteurized milk beverage according to claim 12, which is shelf stable.

14. The pasteurized milk beverage according to any one of claims 1 to 13, which is fermented milk that has been pasteurized after fermentation.

15. A method for producing a sterilized milk beverage according to any one of claims 1 to 13, comprising: preparing a raw material liquid containing milk protein, calcium, and phosphate and subjected to primary sterilization; preparing a stabilizer liquid containing an acid milk stabilizer separately from the raw material liquid; acidifying the raw material liquid to obtain an acidic raw material liquid, and then mixing the acidic raw material liquid with the stabilizer liquid to obtain a mixture; and secondarily sterilizing the mixture to obtain the sterilized milk beverage.

16. A method for producing the pasteurized milk beverage according to claim 14, comprising: preparing a raw material liquid containing milk protein, calcium, and phosphate and subjected to primary sterilization; preparing a stabilizer liquid containing an acid milk stabilizer separately from the raw material liquid; adding a fermenting bacterium to the raw material liquid and fermenting the raw material liquid to obtain a fermented liquid, and then mixing the fermented liquid with the stabilizer liquid to obtain a mixture; and secondarily sterilizing the mixture to obtain the pasteurized milk beverage.